How to use compatible numbers to estimate 21 times 12

Yis the midpoint of xz. for each pair of points given, find the coordinates of the third point. 3. x( 5, 5), z(-1,5) 4. z( 2, 8), y(-2, 2) 7 points each xc find the indicated values. 5. b is between a and c. ab = 2x + 1, bc = 3x – 4, and ac = 62. find the value of 'x', and determine if b is a bisector. 7 points each x = bisector: yes or no? 6. m is between l and n. lm = 7x-1, mn = 2x + 4, and ln = 12. find the value of 'x' an determine if m is a bisector. x = bisector: yes or no?